Experts fear Asian oyster health impact

Bacteria effect on humans lacks study, panel is told

Md. official denies risk

December 14, 2004|By Rona Kobell | Rona Kobell,SUN STAFF

If Maryland officials follow through with plans to introduce the Asian oyster into the Chesapeake Bay, they could open the door to a host of human health problems, according to several scientists who testified at a congressional hearing yesterday.

The scientists are concerned about disease-causing microorganisms that naturally occur in some oysters and have been known to cause food poisoning. In rare cases, infections from the species of bacteria, known as Vibrio, can lead to serious illness and even death.

"We obviously need to examine these organisms in Asian oysters," said Dr. Jan L. Powell, an assistant professor at the University of Maryland's School of Medicine, in her testimony before the congressional panel.

FOR THE RECORD - A photo caption on Page 1B of yesterday's editions of The Sun incorrectly identified W. Peter Jensen, deputy secretary of Maryland's Department of Natural Resources, as U.S. Rep. Wayne T. Gilchrest.

Rep. Wayne T. Gilchrest, a Maryland Republican, conducted yesterday's hearing in Annapolis, along with Democrats Sen. Barbara A. Mikulski of Maryland and Rep. Robert C. Scott of Virginia. The field hearing's purpose was to assess the health of the bay and discuss how to spend the federal resources available for cleanup.

The administration of Gov. Robert L. Ehrlich Jr. has made restoring the bay's oysters one of its top environmental priorities, and is looking to introduce the Asian oyster because diseases have devastated the native populations. For the past year, the state has funded about $2 million in research projects to determine how the Asian oyster would fare in the bay.

Maryland officials are working with the U.S. Army Corps of Engineers on an environmental impact statement and say they will be ready to make a decision in March on whether to introduce the oyster.

But many scientists say it will take far longer to find answers to the many outstanding issues -- among them whether the Asian oyster will out-compete natives for food and habitat, and whether it will bring in new diseases. A National Academy of Sciences report on the Asian oyster recommended at least five years of study.

Mark Luckenbach, an oyster biologist with the Virginia Institute of Marine Science, said at yesterday's hearing that the human health issue "hasn't been looked at" and that a full study of it and the other issues would take between three to seven years.

Mikulski pressed him on whether the questions could be answered more quickly.

"Our watermen are fidgety. Our seafood processors are anxious," she said. "We need sound science, but we're concerned there will be pressure for an introduction."

Luckenbach replied: "Research has been accelerated this past year. I don't think it can be accelerated much faster."

The Ehrlich administration's aggressive Asian oyster research schedule also concerns scientists in New England and throughout the Mid-Atlantic; they worry that the Asian oysters will migrate from the bay and interfere with their native oyster populations.

Last month, the directors of the Delaware and New Jersey fish and wildlife departments wrote a joint letter to the Atlantic States Marine Fisheries Commission opposing the introduction of a non-native oyster in the Chesapeake Bay.

"The states of New Jersey and Delaware are concerned about recent statements made by Maryland officials and Corps of Engineers personnel," the letter read. "It would appear that these individuals may have pre-judged the issue and are not considering all Environmental Impact Statement alternatives, but rather are moving to expedite the introduction of the non-native oyster with an abundance of optimism and a relative dearth of information."

The University of Maryland's Powell and her colleague, O. Colin Stine, were late additions to yesterday's oyster panel. The professors' concerns became known this month after they responded in an e-mail to an inquiry about the human health issue from Del. Dan K. Morhaim, a Baltimore County Democrat who is a physician.

The professors wrote that the incidences of outbreaks caused by species of Vibrio are higher in Asia and are more likely to cause death, though it's uncertain whether the Asian oyster, known as crassostrea ariakensis, is to blame. The bacteria are also present in animal waste.

The Asian oyster, however, does grow larger and at a faster rate than the native oyster, and therefore could acquire more pathogens.

"If the higher incidence of disease is because the Asian oysters are a better home for the pathogens than the American oyster, then introducing the Asian oysters would be expected to cause the incidence of these diseases to increase in the U.S. and potentially close oyster beds to harvest," the professors wrote to Morhaim.

But W. Peter Jensen, the Maryland Department of Natural Resources' deputy associate secretary and the governor's point person on oysters, said he's not concerned about human health risks from the non-native oyster. He said that researchers at University of Maryland's Center for Marine Biotechnology are studying the human health effects of the Asian oyster and Vibrio.

Also, Jensen said, the National Academy of Sciences' report on non-native oysters indicated that there were no human health risks.

"It's not a problem," Jensen said. "We take the report at face value. They see no health risk."

But the center's director, Yonathan Zohar, said his researchers are funded only to look at oyster diseases and pathogens. Zohar said they are looking at Vibrio in general, but are not studying it in terms of its life-span and spread through the Asian oyster.

"We have all the tools and the expertise," Zohar said. "But we don't have funding to do those studies."